In all boats the goal is to decrease this tendency. On a 26C the tendency is stronger so the need to take preventative action is more important. Learning what to do increases your skill level and gives a more enjoyable sail.
There are several ways to reduce the rounding tendencies. Remember that the rounding up forces are caused by excessive heeling.
In order to do all of this sucessfully you need to understand what your sails should look like and how the different controls affect their shape. A sail has a natural tendency to become fuller and have the draft further aft as the wind increases. This is the opposite of what is desireable. What is wanted is for the sail to become flatter with the draft further forward as the wind increases. To counteract this tendency there are several things that can be done.
1. Tighter halyard tension on both the jib and the main will move the draft forward.
2. Using a traveler to move the boom out without it going up will reduce weatherhelm and healing.
3. Using a boom vang will do the same as the traveler.
4. Bending the mast by using an adjustable back stay makes the sail flatter.
5. Bending the mast with the backstay also tightens the forestay which flattens the jib.
6. Tightening the outhaul on the boom makes the sail flatter.
All these things working together makes the boat heal less and sail faster with better control.